Explain Yasuo ult to me

He is a champion with crazy mobility and defensive capabilities for an offensive champion, why the hell is it okay he can towerdive with his ult with no risk whatsoever?!? Literally last game he ulted me, I was barely in my own tower range, he animates 2 character lengths away from me and tower. Why not punish Yasuos that make bad tower dives?!?!?!??
Rant over

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